Not applicable.
Not applicable.
1. Field of the Invention
This invention pertains to launch tubes, and particularly to a launch tube made using fiberglass reinforced polymer (FRP).
2. Description of the Related Art
A fiberglass reinforced polymer (FRP) launch tube has been made, where a bottom is formed by bonding or gluing a plug inside the tube. However, the force from the explosion of pyrotechnics or other explosive propellants inside the tube can break the adhesive bond between the bottom and the inside wall of the tube. The launch tube must then be repaired or replaced.
A method has been devised for making a fiberglass reinforced polymer (FRP) launch tube that can better withstand the explosive force of pyrotechnics or other explosive propellants. An FRP tube is made, and a groove is formed inside the tube adjacent one end. A bottom is engaged with the groove so that axial forces during the explosion are transmitted to the tube. Thus, rather than relying on the bond strength of an adhesive to hold a bottom, the bottom is instead engaged with the FRP tube by its extension into the circumferential groove.
The launch tube may be formed by positioning a mold inside the launch tube adjacent the groove and molding FRP to form the bottom. Such molding may include a compound such as Sheet Molding Compound (SMC), Bulk Molding Compound (BMC) or Low Pressure Molding Compound (LPMC).
A molding resin can be laid on the mold and compressed or vacuum set to squeeze the fiberglass and resin into the groove. Alternatively, a bottom can be pressed into the tube, where the bottom compresses and then expands into the groove. The bottom and the tube form a chamber for receiving pyrotechnics or explosive propellants, and the bottom preferably has a convex surface for defining the chamber. In this manner, explosive forces press the bottom into tighter or deeper engagement with the tube groove.
A launch tube made according to such methods is thus better able to withstand the explosive forces as pyrotechnics or explosive propellants are discharged from the tube.